Enable "File > open" tests for Replay tests

[jamesderlin]

I added a MemoryFileSystem-based implementation of RandomAccessFile in #136. I enabled File > Open tests for test/memory_test.dart, but I did not notice that various other tests depend on MemoryFileSystem and also explicitly disable File > open tests.

Attempting to enable File > open tests in test/replay_test.dart generates lots of errors that I don't yet understand:

test/replay_test.dart: Replay common File open READ RandomAccessFile read rerun read [E]
  type 'List<dynamic>' is not a subtype of type 'Uint8List' of 'input'
  package:file/src/backends/record_replay/codecs.dart                          Passthrough.convert
  package:file/src/backends/record_replay/replay_proxy_mixin.dart 133:30       ReplayProxyMixin.noSuchMethod
  package:file/src/backends/record_replay/replay_random_access_file.dart 17:7  ReplayRandomAccessFile.readSync
  test/common_tests.dart 1825:41                                               runCommonTests.<fn>.<fn>.<fn>.testRandomAccessFileOperations.<fn>.<fn>.<fn>

test/replay_test.dart: Replay common File open READ RandomAccessFile read rerun readIntoWithBufferLargerThanContent [E]
  No matching invocation found: readIntoSync(Instance(length:1024) of '_GrowableList'0, null, )
  package:file/src/backends/record_replay/replay_proxy_mixin.dart 125:7        ReplayProxyMixin.noSuchMethod
  package:file/src/backends/record_replay/replay_random_access_file.dart 17:7  ReplayRandomAccessFile.readIntoSync
  test/common_tests.dart 1832:37                                               runCommonTests.<fn>.<fn>.<fn>.testRandomAccessFileOperations.<fn>.<fn>.<fn>

[jamesderlin]

I looked into the failures.

Failure type 1:

type 'List' is not a subtype of type 'Uint8List' of 'input'

ReplayRandomAccessFile currently uses const Passthrough<Uint8List>() for the #readSync converter. The input is a List<int> that isn't a Uint8List. I don't yet understand why.

Failure type 2:

No matching invocation found: readIntoSync(Instance(length:1024) of '_GrowableList', 0, null)

This happens because on the recording side, we write the event to the manifest after invoking the method, but the method mutates the supplied List argument, so we write the mutated argument, not the original one. The replay side then fails to find the corresponding entry since the List argument no longer matches.

[jamesderlin]

ReplayRandomAccessFile currently uses const Passthrough<Uint8List>() for the #readSync converter. The input is a List<int> that isn't a Uint8List. I don't yet understand why.

The data is serialized as a JSON array of integers, so I think an explicit conversion to Uint8List should be expected.

This happens because on the recording side, we write the event to the manifest after invoking the method,

Maybe RecordingProxyMixin.noSuchMethod could eagerly encode the argument lists to JSON and pass them directly to LiveMethodEvent.

[jamesderlin]

Ugh, there is yet another problem in that there's currently no way for record/replay to replicate mutations to method arguments. The recording site probably would need to encode the arguments before invocation and after, and then the replay side would need to figure out how to update arguments in-place. Or maybe there could be some less general mechanism since all of this would be needed only for RandomFileAccess.readInto/readIntoSync.

[jamesderlin]

This is no longer relevant since record/replay was removed by #162.